The right-hander, projected as one of the club's starters, has been slowed this spring because of tightness in his right shoulder. He will have a flat-ground session on Saturday, and the Cubs will decide if he's ready to take that next step and get on the mound after that.

"We're going to take it day by day," Arrieta said Friday. "Every day's been good. It's gotten progressively better. If we stay on the same schedule, I'm optimistic I'll be ready by Opening Day."